我試圖覆蓋內部類JPanel中的方法paintComponent並繪製一些圖片。但如果我在構造函數中加載圖像,paintComponent方法不會調用。如果在主類中加載圖像,everythig很好。它是什麼?下面的代碼,這一點兒也不工作內部類奇怪的事情JPanel
import java.awt.Graphics;
import java.awt.Image;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main {
JFrame window;
//Image image=new ImageIcon("D://domik.png").getImage();
class JPanelExt extends JPanel {
Image image;
public JPanelExt(){
image=new ImageIcon("D://domik.png").getImage();
System.out.println("constructor");
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
System.out.println("paint");
g.drawImage(image, 0, 0, this);
g.drawRect(0, 400, 100, 100);
}
}
public Main(){
window=new JFrame("Flowers");
window.setSize(430, 480);
window.setVisible(true);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanelExt flower1 =new JPanelExt();
flower1.setBounds(100, 100, 200, 200);
flower1.setToolTipText("House");
window.setLayout(null);
window.add(flower1);
}
public static void main(String[] args) {
Main main=new Main();
}
}
而且系統輸出只寫「構造」
但如果我更改代碼這樣
public class Main {
JFrame window;
Image image=new ImageIcon("D://domik.png").getImage();
class JPanelExt extends JPanel {
//Image image;
public JPanelExt(){
//image=new ImageIcon("D://domik.png").getImage();
System.out.println("constructor");
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
System.out.println("paint");
g.drawImage(image, 0, 0, this);
g.drawRect(0, 400, 100, 100);
}
而且系統輸出寫道:「構造」,「油漆「
我不明白這一點))
最後通過調用'setVisible'開始,並使用合適的佈局管理器 – MadProgrammer
您還應該查看[Initial Threads](http://docs.oracle.com/javase/tutorial/uiswing/concurrency) /initial.html) – MadProgrammer
此外,不要提供'絕對路徑',請參考此[答案](http://stackoverflow.com/a/11372350/1057230),爲應用程序添加圖像。 –